June 14, 2011 -- Sunscreen labels will carry a "broad spectrum" label to show they offer some protection against UVA radiation as well as UVB radiation, according to a long-awaited new rule from the FDA.

The old "SPF" designation still will show how well a product protects against UVB, although the highest SPF level a product can claim will be "50+."

The "broad spectrum" designation carries a lot less information than a zero-to-four-star system the FDA originally proposed for UVA protection. But the FDA did hold firm on insisting that sunscreens claiming swim/sweat protection say how many minutes such protection lasts.

"FDA has evaluated the data and developed testing and labeling requirements for sunscreen products, so that manufacturers can modernize their product information and consumers can be well informed on which products offer the greatest benefit," said Janet Woodcock, MD, director of the FDA's Center for Drug Evaluation and Research.

UVB radiation is responsible for sunburn and plays a major role in causing skin cancer. It affects only the outer layer of the skin. UVA, while less intense than UVB, is 30 to 50 times more prevalent than UVB and penetrates to deeper layers of the skin. UVA is the dominant tanning ray, and is closely linked to skin aging. It's also damages skin DNA and is believed to cause skin cancer.

The new rule also says that products cannot claim an SPF factor higher than 50. The highest permitted rating will be "50+," because the FDA says there's no convincing data that SPF levels higher than 50 are meaningful.

The FDA will allow product labels to carry the claim that they prevent skin cancer -- but only if they protect against UVA and have an SPF of 15 or higher.

Products will have to specify whether they protect only against UVB (SPF rating alone) or whether they protect against UVA as well as UVB (SPF rating plus "broad spectrum" claim).

Sunscreen products that claim to be water resistant will have to undergo water-resistance testing. They will have to specify the number of minutes of "swimming/sweating" for which the product continues to protect.

Consumer groups wanted a lot more from the FDA, which has been mulling the new rules since 1978.

"It's now been 33 years since FDA first announced plans to implement safety standards for sunscreens," Environmental Working Group spokesman Alex Formuzis tells WebMD. "When FDA drags its feet for more than three decades to set up some standards for the sunscreen industry, it's clearly not the federal government's finest effort."

The new rules will take effect in one year for most manufacturers, although those with annual sales of less than $25,000 have two years to comply.